Mechanical trip means for circuit breaker current limiting device combination



Feb. 25, 1958 w. H. EDMUNDS 2,824,929

MECHANICAL TRIP MEANS FOR CIRCUIT BREAKER CURRENT LIMITING DEVICECOMBINATION Flled Nov 12 1954 2 Sheets-Sheet l 3125c T/ON FOR Qa/NG AdaFeb. 25, 1958 w. H. EDMUNDS 2,824,929

MECHANICAL TRIP MEANS FOR CIRCUIT BREAKER CURRENT LIMITING DEVICECOMBINATION Filed Nov. 12, 1954 2 Sheets-Sheet 2 IN V EN TOR. lama/19o;19/94 040 [DMZ/N05 United States Patent MECHANICAL TRIP MEANS FORCIRCUIT BREAKER CURRENT LIMITING DEVICE COMBINATION William HaroldEdmunds, Havertown, Pa., assignor to I-T-E Circuit Breaker Company,Philadelphia, Pa., a corporation of Pennsylvania Application November12, 1954, Serial No. 468,343

3 Claims. (Cl. 200-116) My invention relates to circuit protectiveequipment which electrically and mechanically coordinates a currentlimiting device with a circuit breaker and more particularly is directedto a novel arrangement wherein the force of a current limiting devicetrip pin is multiplied by means of a linkage mechanism in order to tripa large air circuit breaker.

In my copending applications Serial No. 316,221, filed October 22, 1952,and Serial No. 461,378, filed October 11, 1954, I have shown a multiplecircuit breaker with a current limiting device electrically andmechanically associated with each pole.

The current limiting device may have an integral construction of thetype shown in Patent No. 2,592,399, issued April 8, 1952, so that it isresponsive to the rate of current rise and will interrupt severeshort-circuit currents within less than a quarter of a cycle. That is,the letthrough current for the current limiting device may be a smallpercentage of the available short-circuit current which the circuit iscapable of delivering. This device is coordinated with the standard timedelay and instantaneous trip units of the circuit breaker so that forall current magnitudes below a first predetermined value, either theinstantaneous or the time delay trip unit of the circuit breaker willinitiate simultaneous opening of all of the cooperating contacts of thecircuit breaker.

In the event a fault current is above a first predetermined magnitude,then the current limiting device will rupturebefore the trip units ofthe circuit breaker operate. In order to prevent single phasing, thecurrent limiting device is provided with a striker pin which, when thefusible element ruptures, will be driven forward to impart a hammer-blowforce on the tripper bar of the circuit breaker so that all thecooperating contacts thereof will be simultaneously opened.

With this arrangement of electrical and mechanical coordination, betweenthe circuit breaker and the current limiting device, the interruptingcapacity requirements of the circuit breaker is substantially reducedand does not have to be equal to the magnitude of the availableshort-circuit current which the circuit is capable of delivering. Thus,as fully disclosed in copending application Serial No. 461,378, filedOctober 11, 1954, the use of this coordinated device is particularlyapplicable to low voltage, high current circuit application.

As noted in the above identified copending applications, the striker pinof the current limiting device operates directly on the tripper bar ofthe circuit breaker. However, in an air circuit breaker having a steelback of the type shown in copending applications Serial No. 254,349,filed November 1, 1951, Serial No. 423,782, filed April 16, 1954, andSerial No. 445,094, filed July 22, 1954, a force is required to rotatethe tripper bar in order to release the common latch to permit theoperating mechanism to move the cooperating contacts to their disengagedposition. Thus, in air circuit breakers with steel backs, it is notpresently feasible to have the striker pin to operate directly on thecommon tripper Ice 2,824,929

bar since there is an insufficient force available to ro-' tate the tripbar to achieve release of the latching surfaces.

My instant invention is directed to a novel arrangement wherein theforce on the striker pin, which is released when the current limitingdevice ruptures, is multiplied through a linkage mechanism to therebyinsure operation of the common tripper bar whenever one of the currentlimiting devices ruptures.

Accordingly, a primary object of my invention is to provide a circuitbreaker-current limiter combination in which electrical and mechanicalcoordination is achieved between the protective devices with a forcemultiplying means so that a current limiting device striker pin will becapable of rotating the common tripper bar when the devices rupture.

Another object of my invention is to provide a link mechanism between acurrent limiting device and a common tripper bar of a circuit breaker sothat a relatively small force released by the rupture of the currentlimiting device will be multiplied so that all the cooperating contactsof the circuit breaker will be simultaneously opened whenever thecurrent limiting device interrupts a current flowing in the poleassociated therewith.

These and other objects will be apparent from the following descriptionwhen taken in connection with the drawings in which:

Figure 1 is a perspective view of an air circuit breaker.

The circuit breaker can be tripped by either the time delay armature142, the instantaneous armature 143 or the current limiting device 16.

Figure 2 is a partial side view illustrating a current limiting deviceelectrically associated with each pole and mechanically associated withthe circuit breaker.

For the sake of simplicity, the illustration of Figure 1 shows a singlepole of a muiti-pole circuit breaker. However, it will be apparent thatalthough there is a common latch 185-186 and a common cradle and latchfor all poles of the circuit breaker, there is a time delay trip unit,an instantaneous trip unit and a current limiting device associated witheach pole of the circuit breaker, each of which in turn operates on thecommon tripper bar 170.

The operation of the circuit breaker is as follows.

On the occurrence of an overcurrent or fault current sufiicient toenergize the magnets of either the time delay armature 142 or theinstantaneous armature 143, so that these units will function prior tothe operation of the current limiting device 10, the operated armaturewill rotate in a clockwise direction thereby engaging the extension 146on the shaft 140.

The rotation of shaft causes a link 162 to be moved through angle 163.The transitory movement of link 162 causes the rotation of the commontripper bar which is the common tripper bar of the circuit breaker. Thecounterclockwise rotation of the common tripper bar 170 releases thelatch 1851S6 thereby resulting in the automatic movement of thecooperating contacts 6061 from their engaged to their disengagedposition, as seen in Figure 1.

It will be noted that the common tripper bar 178 has an abutment 178which may be engaged by the roller 179 which, in turn, is rotated bymeans of the manual handle 184. The manual handle 1554 is attached tothe shaft 180 which, in turn, is rotated by means of the manual handle184. The manual handle 184 is attached to the shaft 180 which, in tum,has a crank 181 rigidly attached thereto with the roller 179 on one endthereof. Thus, when the shaft 180 is rotated by the closing handle 184,the roller 179 engages the abutment 173 to rotate the common tripper bar170 in a clockwise direction so that the cooperating contacts 6il61 canbe moved from their engaged to their disengaged position.

Patented Feb. 25, 1958- As will hereinafter be more fully explained, thecommon tripper bar 170 can also be rotated by means of the .currentlimiting devices a, 10b or 100 which operate through a linkage mechanismto impart aforce thereto. Thus, the circuit breaker can be opened byeither the time delay armature 142, the instantaneous armature 143, thecurrent limiting device 10, or manually by means of the handle 184.

The latch surface 177 is an integral part of the trip arm 185 andengages the milled section 186 of the common tripper bar 171) so that asmall angular rotation of the common tripper bar 1711 will release thelatch 177- 186.

The trip arm 135 is pivoted at 187 on a long pin 188. The pin 188 isalso engaged on the trip arm extension 189 at point 133. The movable arm190 is pivoted on pin 138 and extends beneath a'roller'193. The roller193 is the pivot point of a toggle mechanism consisting of two links 194and 195 and is carried by a pin 202 which pivots the meeting of links194 and 195 which are each comprised of two arms. Arms 194 are pivotedon floating pin 196 and arms 195 are pivoted on pin 204.

The arms 194 support a rod 197 at 198 and 199, respectively. The rod 197carries one end of a restoring spring 233 which is tensed by means of astationary shaft.

The restoring spring 2113 exerts a tension on the link 194 which tendsto open or break the toggle mechanism. Link 194 is pivoted on a floatingpin 196 which is supported by link arm 185 and its extension 189 beingparallel to the pin 138. The other link 195 of the toggle is pivoted onmovable link 2011 which is connected by means of an adjustable insulator201 to the movable contact assembly 61 and pivoted on contact bar 406.

When the toggle mechanism consisting of links 194 and 195 isstraightened out by means hereinafter described, pressure is put onmovable link 2110 by means of link 195 and bearing pin 2114. The movablelink 200 is pinned to insulator 2d by pin 2 35 and moves so as toadvance the insulator 2111 and the movable contacts61 towards thestationary contact 619.

In the exploded view shown in Figure l, the contacts are open and thetoggle mechanism consisting of links 194 and 195 is collapsed. Thecircuit breaker may be closed by a variety of methods. The circuit canbe closed manually by means of shaft 180 rotated by closing handle 134,described above. If shaft 18% is rotated in the direction indicated byarrow 184a, the roller 179 will engage the bottom of arm 1% and forcethe arm 190 against roller 193 thus straightening out the togglemechanism and closing the circuit breaker contacts 6tl-61.

The movable links 2% are under an opening tension by means of openingspring 211! so that if no additional locking action other than describedabove for supporting the toggle existed, the circuit breaker wouldreopen immediately upon releasing the shaft 180. The locking device issupplied by means of a prop latch 211 which is located on a shaft 212whose longitudinal axis is parallel to the .axis of the milled shaft170, and the rod 140. The prop latch 211 has two arms 213 and 214.

The latch surface 213 is located, when the circuit breaker is open,adjacent the roller 193. When the roller 193 is forced upward, as due tothe pressure of arm 190, the roller pushes against prop latch 211rotating the prop latch 211 on shaft 212. When the roller 193 hascleared the top of prop latch 213, the prop latch 213 snaps underneaththe roller 193 due to the compression of biasing spring 220. The spring220 which is wound on the shaft 212 has one end on an indentation 221 ofcrank 211, the other end borne against a shaft 222 which pierces thetrip arm 185. The shafts 212 and 222 have been moved out of position inthe exploded view for the sake of clarity. Actually, t1 e shaft 222pierces the triparm 155 at point 297.. The longitudinal axis of;shaft222 is-.. essen tially parallel to the longitudinal axis of shaft212andmilled shaft 170.

When the roller 193 is moved, straightening the toggle, it causes thecrank 211 to rotate compressing spring 220. The roller clears the top ofprop latch 213 letting the crank rotate in the opposite direction untilthe prop latch surface 213 is directly beneath and supporting the roller193. The other arm 214 of prop latch 211 bears against the shaft 222preventing further rotation of the crank 211 so that the latch surface213 is stopped directly beneath the roller 193. The spring 220 is undercompression normally so that the arm 214 is constantly bearing againstthe shaft 222. .When the toggle is straightened the rotation of the proplatch 211 moves the arm214away from the. shaft 222 until the roller 193clears the top of prop latch 213. Then the reverse rotation of the crank211 occurs until the arm 214 again bearsagainst the shaft 212.

Thus, when the toggle is straightened and the circuit breaker closed,the prop latch 211 locks the toggle 194-195 and thus locks-the circuitbreaker in a closed position.

The closing handle 184, by means of the shaft 180, after closing'thecircuit breaker by means of the rotations of roller 179 against the arm190, as described above, is returned to its normal position by means ofa crank 230. The crank 231) is pivoted on a stationary pin 231.

The crank'181 described above has an indentation 232 which meets aroller 233 of crank 230. The crank 2311 supports pin 234 which has arestraining spring 235 engaged at one end 236. The restraining spring235 is attached to an angle 237 and is tensed on the pin 236 causing thecrank 231i to rotate. The rotation of crank 23% causes the roller 233 tomeet the indentation 232 returning the crank 181 to its normal position.

' The circuit breaker may also be closed by closing means 301i, 241 asdisclosed in copending application Serial No.

383,714, filed October 2, 1953.

As heretofore noted, the circuit breaker is provided with a timedelayitrip armature 142 and an instantaneous trip armature 143 whichfunction in a manner well known in the art as, for example, described incopending application Serial No. 254,359, filed November 1, 1951. 7

Also as heretofore noted, the circuit breaker is provided with a currentlimiting unit which is both an interrupting device and a trip unit. Thecurrent limiting device 10 has a fusible element with a plurality ofreduced cross-sectional areas and is surrounded by quartz crystal. Theunit is also provided with a striker pin 11 which is normallyinoperative.

The construction whereby the stored energy for the striker pin 11 isreleased upon thesrupturing of a fusible element, is shown in copendingapplication Serial No. 316,221, filed October 22, 1952, and Serial No.461,378, filed October 11, 1954.

The current limiting device 10 has electrical terminals 12 and 13 bywhich it is connected inelectrical series with the cooperating contactsv6tl61 of the phase or pole with which it is associated. Thus, forexample, as seen in the figures, the current limiting device 10 isremovably retained within theclip terminal means 14-15. Thus, for eachpole of the circuit breaker, the current will flow from the sourcethrough the current limiting device 10 through the cooperating contacts60-61 to the load. Each current limiting device 10 is positioned so thatits striker pin is in close proximity to the lever '16. A common bar 18is provided with an extension lever 16a, 16b, 16c respectively extendingtherefrom for each pole of the circuit breaker. The common bar 18 ispivoted around fixed pivot 19 .and the extension lever 16 is rigidlyattached thereto.

136F213 threadably engaging the-end sections 22-24 so that the effectivelength of the rod can be adjusted 4 by altering the threaded engagementbetween'the three members;

The top end of the rod 20 has a member 23 pivotally mounted thereon atpoint 24'. The member 23 contains openings to receive the screws 25 and26. A plate 27 is positioned on one side of the common tripper bar 170and the screws 25-26 which extend through the plate 27 are in threadableengagement with the plate 27'. Hence, the plate 27 is effectively boltedto the common tripper bar 170.

On the occurrence of a severe short-circuit current, the currentlimiting device will rupture thereby interrupting the current flow inthe phase with which it is associated. The ruptured portion of thecurrent limiting device 10 will permit a spring to release stored energyso that the striker pin 11 will be driven upwardly thereby rotating itsassociated extension bar 16 in a counterclockwise direction around thefixed pivot 19. This rotation will pull the rod 20 downwardly therebycausing the left-hand end of the plate 27 to rotate downwardly.

This motion will cause the common tripper bar 170 to be rotated in acounterclockwise direction to thereby release the latch 177-186. Thus,the striker pin 10 is operatively connected to the common tripper bar170 by means of linkage mechanism 16-20.

By providing a long arm of the extension lever 16 on the right of pivot19 and a relatively short arm on the left of this pivot, it is possibleto multiply the force on the striker pin 11. Thus, even though arelatively large force is required to rotate the common tripper bar 170,a relatively small force driving the striker pin upwardly will bemultiplied through linkage mechanism 16-20 so that a sufiicient force isimparted to the plate 27 to rotate the common tripper bar 170 in acounterclockwise direction to release the latch 177-186.

Hence, with my novel arrangement, a force multiplying means is providedthrough linkage mechanism so that a relatively small spring can be usedin connection with the current limiting device 10 and still obtainsutficient force to rotate the common tripper bar and release the latchof the circuit breaker.

In the foregoing, I have described my invention only in connection withpreferred embodiments thereof. Many variations and modifications of theprinciples of my inven tion within the scope of the description hereinare obvious. Accordingly, I prefer to be bound not by the specificdisclosure herein, but only by the appending claims.

I claim:

1. A circuit protective arrangement comprised of a multipole circuitbreaker and a current limiting device associated with each pole thereof;each pole of said circuit breaker having a pair of cooperating contactsand a first trip means; said first trip means operatively connected to acommon tripper bar to effect simultaneous disengagement of thecooperating contacts associated with each pole of said circuit breaker;said first trip device rendered operative on the occurrence of a faultcurrent below a first predetermined current magnitude; each of said pairof cooperating contacts having a current limiting device connected inelectrical series therewith; said current limiting device effective tointerrupt current flow above said first predetermined current magnitude;said current limiting device having a striker pin normally held in aninoperative position; a mechanical device operatively connecting each ofsaid striker pins to said common tripper bar; said mechanical devicebeing comprised of an auxiliary common tripper bar and a linkage; saidauxiliary common tripper bar having relatively long extensions extendingin a direction and positioned to be engaged respectively by said strikerpin of one of said current limiting devices associated therewith; saidauxiliary common tripper bar having a relatively short extension; saidshort extension being operatively connected to said common tripper barby said linkage; said auxiliary common tripper bar along with itsplurality of long extensions and short extension serving as a forcemultiplying means for said current limiting devices.

2. A circuit protective arrangement comprised of a multipole circuitbreaker and a current limiting device associated with each pole thereof;each pole of said circuit breaker having a pair of cooperating contactsand a first trip means; said first trip means operatively connected to acommon tripper bar to efiect simultaneous disengagement of thecooperating contacts associated with each pole of said circuit breaker;said first trip device rendered operative on the occurrence of a faultcurrent below a first predetermined current magnitude; each of said pairof cooperating contacts having a current limiting device connected inelectrical series therewith; said current limiting device effective tointerrupt current flow above a first predetermined current magnitude;said current limiting device having a striker pin normally held in aninoperative position; mechanical means operatively connected betweensaid striker pin and said common tripper bar; said striker pinoperatively connected to rotate said common tripper bar through saidmechanical means when said current limiting device interrupts saidcircuit; said mechanical means being comprised of an auxiliary commontripper bar and a linkage member to multiply the force of said strikerpin to a magnitude sufficient to rotate said common tripper bar; saidauxiliary common tripper bar having a plurality of long extensionscorresponding to the number of poles of said circuit breaker and havingone of said current limiting devices associated respectively with eachof said long extensions; a short extension from said auxiliary commontripper bar, one end of said linkage connected to said common tripperbar and the other end of said linkage connected to said short extension;said linkage being adjustable in length.

3. A multi-pole automatic circuit interrupter being comprised of pairsof cooperating contacts, manual control means, operating mechanism andtrip elements; said operating mechanism containing a common tripper bar;a current limiting device associated with each pair of said cooperatingcontacts; said pairs of cooperating contacts having an engaged anddisengaged position; said manual control means, said trip elements andsaid current limiting devices being operative through said commontripper bar of said operating mechanism to effect movement of said pairsof cooperating contacts from said engaged position to said disengagedposition; each of said current limiting devices having a stored energymeans releasable on the occurrence of a predetermined fault current; anauxiliary common tripper bar; said auxiliary common tripper bar having aplurality of long extensions and a short extension; said short extensionfrom said auxiliary common tripper bar connected to said common tripperbar by a linkage; said linkage being adjustable; said plurality of longextensions from said auxiliary common tripper bar each being positionedrespectively for engagement by said stored energy device of said currentlimiting device associated therewith; each of said current limitingdevices operative to move said common tripper bar through said longextension, said auxiliary common tripper bar, said short extension andsaid adjustable linkage.

References Cited in the file of this patent UNITED STATES PATENTS2,306,153 Biermanns et al Dec. 22, 1942 2,330,690 Dannenberg Sept. 28,1943 2,473,196 Dannenberg June 14, 1949

